The temporary breakdown of Earth’s magnetic field 42,000 years ago caused a major one climate changes leading to global environmental changes and mass extinctions.
As a new international study co-led by the University of New South Wales (UNSW), Sydney and the Museum of South Australia shows, this dramatic turning point in Earth’s history was mixed with thunderstorms, widespread auroras and cosmic rays. caused by the reversal of the Earth’s magnetic poles and changing solar winds. The findings are published in Science (Also read: Researchers make objects float powered by light).
“For the first time in history, we have been able to accurately date the timing and environmental impact of the last magnetic polar reversal”says Chris Turney, a professor at UNSW and a co-lead author of the study.
The finds were made possible by ancient New Zealand kauri trees, which have been preserved in sediments for more than 40,000 years. “Using the ancient trees, we were able to measure and date the increase in atmospheric radiocarbon levels caused by the collapse of the Earth’s magnetic field,” Turney said in a statement.
While scientists already knew that the magnetic poles were temporarily reversed 41-42,000 years ago, They weren’t quite sure how it affected life on Earth, if at all. But the researchers were able to create a detailed timetable of how Earth’s atmosphere changed during this time by analyzing the rings in ancient kauri trees.
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“Kauri trees are like the Rosetta Stone, helping us unify the records of environmental change in caves, ice cores and peat bogs around the world.”says co-lead professor Alan Cooper, an honorary researcher at the Museum of South Australia.
The researchers compared the newly created timescale with data from locations in the Pacific Ocean and used it in modeling the global climate, finding that the growth of ice sheets and glaciers in North America and major changes in the major wind belts and tropical storm systems may have been traced to the Adams Event, named by researchers after British science fiction writer Douglas Adams.
It was a time when seemingly random cosmic events and extreme environmental changes coincided Found around the world 42,000 years ago.
One of his earliest indications was that megafauna in mainland Australia and Tasmania were simultaneously extinct during that period.
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“This never seemed correct, as it was long after the arrival of the Aborigines, but it was around the same time that the Australian environment changed to its current arid state,” said Professor Cooper. The paper suggests the event could explain many other evolutionary mysteries, such as the extinction of Neanderthals and the sudden and widespread appearance of figurative art in caves around the world.
Colombian physicist Santiago Andrés Triana of the Royal Observatory of Belgium notes this Reversing the magnetic poles is a phenomenon that has occurred many times in the past and the exact causes of which are not fully understood.
“We know that the magnetic field is generated by a dynamo effect in the liquid core of the earth. Currents in that ocean of liquid iron generate magnetic fields which in turn provide more energy to these currents, in a feedback process that results in a large-scale magnetic field as we now perceive it. However, this process is not completely stable. The magnetic reversal of 42,000 years ago is proof of this, ”says Triana.
Triana adds that “during this relatively short period of reverse polarity, the intensity of the magnetic field was much less than the normal intensity. This allows more radiation from electrically charged particles from the sun to reach the surface of our planet, causing significant damage to the ozone layer and in turn affecting the climate and the environment in general ”.
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According to Triana, the magnetic field is currently weakening, albeit at a relatively slow rate: “ We also know that there are periodic ‘shocks’ in the magnetic field, as is currently shown by the rapid drift of the magnetic North Pole from Canada. to Siberia.
The magnetic inversion revealed by the Laschamps event, as the phenomenon described in the study is called, shows that surprising changes in the interior of the Earth can occur at a very fast time scale (geologically speaking) and that they affect the habitability of our planet. can affect negatively. . That is why it is important to study and understand the processes that take place in the core of the earth as closely as possible. Our future may depend on it, ”says Triana.
EUROPE PRESS